Design of 98.8% Efficient 400-to-48-V LLC Converter With Optimized Matrix Transformer and Matrix Inductor

In recent years, there has been a considerable upswing in power usage by data centers. As a result, the 48-V power architecture has become increasingly favored due to its high efficiency. However, the cost of efficient power supplies remains challenging due to their complicated magnetic designs. The search for efficient and cost-effective power supplies continues. This article focuses on the implementation of the dc-dc stage of the power supply unit for the 48-V data center bus architecture. In this article, we present a design process for a high-efficiency high-power-density 3-kW 400-to-48-V LLC converter for use in data centers. Through the optimization of the matrix transformer's geometry, turn number, and resonant frequency, we achieve superior efficiency and power density compared to state-of-the-art designs. To address challenges with the printed circuit board (PCB)-based inductors, we propose the use of a resonant matrix inductor, which reduces the number of stacked PCB layers, simplifies the winding implementation, and lowers the ac loss. By integrating the matrix inductor with the matrix transformer, we create a modular and scalable magnetic structure suitable for a wide range of voltages and currents. We also introduce electromagnetic interference shielding for the matrix transformer with a full-bridge rectifier, resulting in an 18-dB reduction in common-mode noise. The prototype achieved a peak efficiency of 98.8% and a power density of 600 W/in(3), demonstrating the effectiveness of the proposed design.